In addition, how information is structured has an impact on how catalogues and databases are searched.

When a word search is done in the OPAC all words in the author's last name index, every word in the title field, each word in the subject heading field, and all words in the table of contents field are searched.
When a search is done in a database, such as ERIC, all words in titles, descriptors, identifiers, authors, journal names, and abstracts are searched.
In the OPAC it possible to search for words just in the Title, Author, or Subject field.
In databases, such as ERIC, it is possible to limit searches to just about any field.